CN105547463A - Monitoring system and method for vibration signal of on-load tap changer of power transformer - Google Patents

Abstract

The invention discloses a vibration signal monitoring system and method for an on-load tap changer of a power transformer, comprising: a vibration sensor arranged on the on-load tap-changer to sense the vibration signal generated by the on-load tap-changer; a data acquisition instrument, It is connected with the vibration sensor signal, collects the vibration signal and converts it into a time-domain and frequency-domain atlas; a monitoring unit is connected with the data acquisition instrument signal, and uses software to realize the comparison of each atlas. The invention can carry out state monitoring and fault analysis on the on-load tap changer under the condition that the transformer does not hang the core, so as to achieve the purpose of improving the maintenance quality of the on-load tap changer.

Description

A power transformer on-load tap changer vibration signal monitoring system and method

technical field

The invention relates to the field of transformer equipment state monitoring, in particular to a system and method for monitoring vibration signals of an on-load tap changer of a power transformer.

Background technique

The on-load tap-changer can not only stabilize the load center voltage, but also is an indispensable important equipment for connecting the power grid, adjusting the load flow and improving reactive power distribution. However, as the only part of the transformer that moves quickly under high voltage and high current, the on-load tap-changer has very strict requirements on mechanical properties, so the failure rate is relatively high in the initial stage of its promotion, which affects the safe operation of the power grid.

At present, under the condition that the overall failure rate of transformers is low, on-load tap-changer failures still account for a relatively large proportion. The reliability of the on-load tap-changer is generally guaranteed by periodic planned maintenance (oil change and lifting core, etc.). The maintenance work is usually completed by several people in half a day to one day. The key test items are mostly carried out after lifting the core. , the workload of a suspension core is almost equivalent to a major repair, and the condition maintenance of equipment has become an inevitable trend of power grid maintenance. If a new condition monitoring and fault diagnosis technology can be provided for the on-load tap-changer, and the maintenance period can be extended under the premise of ensuring its reliability, it means that the maintenance cost will be reduced; in addition, some on-load tap-changer failure and maintenance It is difficult to find the human error of personnel in the current maintenance, and the adoption of new condition monitoring and fault diagnosis technology is also conducive to further improving the quality of maintenance.

Contents of the invention

The purpose of the present invention is to provide a power transformer on-load tap-changer vibration signal monitoring system and method, which can perform state monitoring and fault analysis on the on-load tap-changer when the transformer is not suspended, so as to improve the on-load tap-changer. The purpose of switching overhaul quality.

In order to achieve the above and other purposes, the present invention provides a power transformer on-load tap changer vibration signal monitoring system and method, including:

The vibration sensor is arranged on the on-load tap-changer to sense the vibration signal generated by the on-load tap-changer;

A data acquisition instrument, connected to the vibration sensor signal, collects the vibration signal and converts it into time domain and frequency domain atlas;

The monitoring unit is connected to the signal of the data acquisition instrument, and compares the time domain spectrum produced by the data acquisition instrument with the time domain spectrum of the normal state. If the characteristics of the spectrum match, it will be displayed as a normal state; if the characteristics of the spectrum do not match , compare it with a variety of common fault time-domain atlases, and if the characteristics of the atlases match, compare the frequency-domain atlas generated by the data acquisition instrument with the frequency-domain atlas in the normal state for energy spectrum analysis. If the energy ratios are consistent, it will be displayed as a normal state; if the energy ratios are inconsistent, compare them with the energy ratios of energy spectrum analysis of frequency domain maps of various common faults. If the energy ratios are consistent, the corresponding faults will be displayed. If the energy ratios are If the ratio does not match, it will be displayed as a new fault.

A further feature is that the monitoring unit further includes a storage module, which is used to store the time-domain graph and frequency-domain graph of the normal state and common fault state.

A further feature is that the analysis frequency of the data acquisition instrument is above 20KHz.

The further feature is that the common fault time-domain atlas includes the time-domain atlas of poor fixation of the cylinder, contact wear, ring deformation, static contact loosening, contact jamming, and bracket breakage.

The further feature is that the frequency domain spectrum of common faults includes the frequency domain spectrum of poor fixation of the cylinder, contact lung damage, ring deformation, static contact loosening, contact jamming, and bracket fracture.

A further feature is that the sampling frequency of the vibration sensor is 51.2kHz, the sampling time is 160ms, and the pre-triggering is 60ms.

A further feature is that the vibration sensor is a piezoelectric ICP sensor.

The present invention also provides a power transformer on-load tap changer vibration signal monitoring system and method, comprising the following steps:

Sensing the vibration signal generated by the on-load tap-changer;

Collect vibration signals and convert them into time-domain and frequency-domain spectra;

Compare the time-domain spectrum with the time-domain spectrum of the normal state, if the spectrum features match, it will be displayed as a normal state; if the spectrum features do not match, compare it with a variety of common fault time-domain spectrums, if the spectrum features , compare the frequency domain spectrum with the energy ratio of the frequency domain spectrum in the normal state. If the energy ratio is consistent, it will be displayed as a normal state; The energy ratio of the energy spectrum analysis of the domain map is compared. If the energy ratio is consistent, the corresponding fault will be displayed. If the energy ratio does not match, it will be displayed as a new fault.

It is further characterized in that the energy spectrum analysis method is to calculate the energy ratio of the first frequency range and the energy ratio of the second frequency range in the frequency domain spectrum, wherein the energy ratio of the first frequency range=energy of the first frequency range/total energy*100 %; energy ratio of the second frequency range=energy of the second frequency range/total energy*100%.

It is further characterized in that the first frequency range is 0-10KHz, and the second frequency range is 10KHz-20KHz.

A further feature is that the common fault time-domain atlas includes time-domain atlases of poor fixing of the cylinder, wear of the contact, deformation of the ring, loosening of the static contact, jamming of the contact, and breakage of the bracket.

A further feature is that the frequency domain spectrum of common faults includes frequency domain spectrum of poor fixing of the cylinder, wear of contacts, deformation of rings, looseness of static contacts, jamming of contacts, and broken brackets.

The advantages of the present invention are: the system and method are provided with a vibration sensor on the on-load tap-changer to perceive the vibration signal, so not only can the state monitoring and fault analysis be carried out on the on-load tap-changer under the condition that the transformer is not suspended, It can also be used when the transformer is out of service and when the transformer is live.

Description of drawings

Fig. 1 is a functional block diagram of a power transformer on-load tap changer vibration signal monitoring system provided by an embodiment of the present invention.

Fig. 2 is a flowchart of a method for monitoring vibration signals of an on-load tap changer of a power transformer provided by an embodiment of the present invention.

FIG. 3 is a time-domain and frequency-domain spectrum diagram of a normal state in an embodiment of the present invention.

Fig. 4 is a spectrum in the time domain and frequency domain of poor fixation of the cylinder in an embodiment of the present invention.

Fig. 5 is a diagram of the time domain and frequency domain of the contact wear state in an embodiment of the present invention.

Fig. 6 is a diagram of time domain and frequency domain of ring deformation state in an embodiment of the present invention.

Fig. 7 is a spectrum in the time domain and frequency domain of the static contact loose state in an embodiment of the present invention.

FIG. 8 is a time-domain and frequency-domain spectrum diagram of a stuck contact state in an embodiment of the present invention.

Fig. 9 is the time-domain and frequency-domain spectra of the fractured state of the stent in an embodiment of the present invention.

detailed description

The implementation of the present invention will be described below through specific common examples and in conjunction with the accompanying drawings, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific examples, and various modifications and changes can be made to the details in the specification based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to FIG. 1 , which is a functional block diagram of a vibration signal monitoring system for an on-load tap changer of a power transformer provided by an embodiment of the present invention. As shown in the figure, the system includes a vibration sensor 10 , a data acquisition instrument 20 and a tracking unit 30 . Wherein the vibration sensor 10 is arranged on the on-load tap-changer 1, and senses the vibration signal that the on-load tap-changer 1 produces; the data acquisition instrument 20 is connected with the vibration sensor 10 signal, and gathers the vibration signal that the vibration sensor 10 senses And convert into time domain and frequency domain atlas; Monitoring unit 30 is connected with data acquisition instrument 20 signal, and the time domain atlas that data acquisition instrument 20 produces is compared with the time domain atlas of normal state, if the atlas features match, just show as normal state; if the graph features do not match, then compare it with multiple common fault time domain graphs, if the graph features match, the frequency domain graphs produced by the data acquisition instrument 20 and the frequency domain graphs in the normal state are subjected to energy spectrum analysis If the energy ratio is consistent, it will be displayed as a normal state; if the energy ratio is inconsistent, it will be compared with the energy ratio of the energy spectrum analysis of a variety of common fault frequency domain maps. If the energy ratio is consistent, it will be displayed. The corresponding fault, if the energy ratio does not match, is displayed as a new fault.

Preferably, the vibration sensor 10 is a three-dimensional vibration sensor, which can be fixed on the top position of the cylinder body of the on-load tap changer by using a magnetic base, and the output end of the vibration sensor 10 is connected to the data acquisition instrument 20 through a joint, preferably can be BNC connectors are selected for connection, but of course the present invention is not limited thereto. Because the highest frequency of energy spectrum analysis is 20KHz, the selected data acquisition instrument has an analysis frequency of more than 20KHz and has time domain, frequency domain, and energy spectrum analysis functions. After the vibration signal is collected by the vibration sensor 10, the signal can be converted into time. domain and frequency domain spectra. Vibration sensor 10 selects piezoelectric ICP type sensor for use, and the sampling frequency of vibration collection is 51.2kHz, and sampling time is 160ms, and pre-triggering is 60ms, and just can guarantee the collection of vibration signal like this, certainly, the present invention is not limited to this, the art in the art Technicians can also choose other more sensitive sensors.

Usually, a storage module 31 is provided in the monitoring unit 30 to store the time domain spectrum and frequency domain spectrum of normal state and common failure state. The time-domain spectrum of common faults includes the time-domain spectrum of poor fixation, wear of contacts, ring deformation, loose static contacts, jamming of contacts, and broken brackets. The frequency domain spectrum of common faults includes the frequency domain spectrum of poor fixing of the cylinder, wear of the contact, deformation of the ring, loosening of the static contact, jamming of the contact, and fracture of the bracket.

The data acquisition instrument 20 can output a variety of text formats for ease of use, such as the commonly used excel file format.

Please refer to FIG. 2 , which is a flowchart of a method for monitoring vibration signals of an on-load tap-changer of a power transformer provided by the present invention. As shown in the figure, the method includes the following steps:

S10: sensing the vibration signal generated by the on-load tap changer;

S20: collect vibration signal and convert into time domain and frequency domain atlas;

S30: compare the time-domain atlas with the time-domain atlas of the normal state, if the atlas characteristics match, it will be displayed as a normal state; if the atlas characteristics do not match, then proceed to step S40;

Step S40: compare the time-domain atlas with a variety of common fault time-domain atlases, if the atlas features match, then proceed to step S50:

Step S50: comparing the energy ratio of the energy spectrum analysis between the frequency domain spectrum and the frequency domain spectrum in the normal state, if the energy ratio matches, it will be displayed as a normal state; if the energy ratio does not match, then proceed to step S;

Step S60: compare with the energy ratio of energy spectrum analysis of multiple common fault frequency-domain atlases, if the energy ratio matches, the corresponding fault will be displayed, if the energy ratio does not match, it will be displayed as a new fault;

The energy spectrum analysis method in step S50 is to calculate the energy ratio of the first frequency range and the energy ratio of the second frequency range in the frequency domain map, wherein

Energy ratio in the first frequency range=energy in the first frequency range/total energy*100%;

Energy ratio of the second frequency range=energy of the second frequency range/total energy*100%.

Generally, the selected first frequency range is 0-1KHz, and the second frequency range is 1KHz-20KHz.

The time-domain spectrum of common faults in the vibration signal monitoring system and method of on-load tap-changer of power transformer includes the time-domain spectrum of poor fixing of cylinder body, wear of contacts, deformation of ring, looseness of static contacts, jamming of contacts, and fracture of brackets. The frequency domain spectrum of faults includes the frequency domain spectrum of poor fixing of the cylinder, wear of the contact, deformation of the ring, loosening of the static contact, jamming of the contact, and fracture of the bracket.

Usually, monitoring unit 30 can utilize a PC to realize, in the storage module 32 in the monitoring unit 30, record the time domain and frequency domain diagram of the various normal and fault states of the on-load tap changer earlier, as shown in Figure 3 to As shown in FIG. 9, the time-domain three-dimensional (x, y, z) maps of the normal state and at least six pre-established common fault states are certainly not limited to six, and fault maps in various situations can be established according to specific conditions.

Fault diagnosis adopts comprehensive criteria of time domain comparison and frequency domain energy comparison. Taking the situation of normal state as an example, at first: carry out the entry of time domain and frequency domain map of normal on-load switch operation process, there is certain difference in each on-load switch, as shown in Figure 3, under the normal state of on-load switch Research on the characteristics of the time-domain spectrum: the action process is 60ms to 90ms, two pulses can be seen, the interval between the two pulses must be 20ms, and the amplitude of the two pulses is similar; the low-frequency energy in the frequency-domain spectrum is 80% to 90%, and the high-frequency energy is 10% %~20%.

Then, it is judged that the energy of the time-domain spectrum and spectrum of the on-site detection spectrum is different from the characteristics in Figure 3 as an abnormal situation, and the energy ratio of the detection frequency-domain spectrum is compared with the energy ratio of the common state in the table, and the fault type can be obtained . If there is no map feature in the table in the comparison result of the detected map feature, it will be displayed as a new fault, or the fault type can be analyzed, and the new fault map feature will be added to the storage unit.

The transformer on-load tap-changer state monitoring method of the present invention is based on the classical mechanics theory and the vibration analysis theory, and establishes each state of the on-load tap-changer by simulating various normal and fault states of the on-load tap-changer The characteristics of the time domain map and frequency domain map are compared and comprehensively analyzed to achieve the purpose of transformer on-load tap-changer status monitoring and fault diagnosis.

The method for monitoring the state of the transformer on-load tap changer of the present invention can realize the offline and online state monitoring of the on-load tap changer when the transformer is not suspended.

The transformer on-load tap changer state monitoring method of the present invention can be connected with the state maintenance system of power transmission and transformation equipment and used in cooperation.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Any person skilled in the art can modify and change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be listed in the claims.

Claims (10)

1. A power transformer on-load tap changer vibration signal monitoring system and method, is characterized in that, comprising: The vibration sensor is arranged on the on-load tap-changer to sense the vibration signal generated by the on-load tap-changer; A data acquisition instrument, connected to the vibration sensor signal, collects the vibration signal and converts it into time domain and frequency domain atlas; The monitoring unit is connected with the signal of the data acquisition instrument, compares the time-domain spectrum generated by the data acquisition instrument with the time-domain spectrum of the normal state, and if the characteristics of the spectrum match, it will be displayed as a normal state; if the characteristics of the spectrum do not match, Just compare it with a variety of common fault time-domain graphs, if the graph features match, then compare the frequency domain graph generated by the data acquisition instrument with the energy of the frequency domain graph in the normal state for energy spectrum analysis, if the energy If the energy ratio is consistent, it will be displayed as a normal state. If the energy ratio does not match, it will be compared with the energy ratio of energy spectrum analysis of frequency domain maps of various common faults. If the energy ratio is consistent, the corresponding fault will be displayed. If the energy ratio does not match, It is displayed as a new fault. 2. A power transformer on-load tap changer vibration signal monitoring system and method according to claim 1, characterized in that, the monitoring unit also includes a storage module for storing the normal state and common fault state time-domain and frequency-domain spectra. 3. A power transformer on-load tap changer vibration signal monitoring system and method according to claim 1, characterized in that the analysis frequency of the data acquisition instrument is above 20KHz. 4. A power transformer on-load tap changer vibration signal monitoring system and method according to claim 1, characterized in that, the common fault time-domain atlas includes poor fixing of the cylinder, wear of the contacts, ring deformation, static Time-domain spectra of loose contacts, stuck contacts, and broken brackets. 5. according to a kind of power transformer on-load tap-changer vibration signal monitoring system and method shown in claim 1, it is characterized in that, described common fault frequency-domain atlas includes simplified fixed bad, contact wear, ring deformation, static contact The frequency domain spectrum of loose head, stuck contact and broken bracket. 6. A power transformer on-load tap changer vibration signal monitoring system and method according to claim 1, characterized in that the sampling frequency of the vibration sensor is 51.2kHz, the sampling time is 160ms, and the pre-triggering is 60ms. 7. A power transformer on-load tap changer vibration signal monitoring system and method according to claim 1, characterized in that the vibration sensor is a piezoelectric ICP sensor. 8. A power transformer on-load tap changer vibration signal monitoring system and method, is characterized in that, comprises the steps: Sensing the vibration signal generated by the on-load tap-changer; Collect vibration signals and convert them into time-domain and frequency-domain spectra; Compare the time-domain spectrum with the time-domain spectrum of the normal state, if the spectrum features match, it will be displayed as a normal state; if the spectrum features do not match, compare it with a variety of common fault time-domain spectrums, if the spectrum features , compare the frequency domain spectrum with the energy ratio of the frequency domain spectrum in the normal state. If the energy ratio is consistent, it will be displayed as a normal state. The energy ratio of the energy spectrum analysis of the domain map is compared. If the energy ratio is consistent, the corresponding fault will be displayed. If the energy ratio does not match, it will be displayed as a new fault. 9. power transformer on-load tap changer vibration signal monitoring system and method according to claim 8, is characterized in that, described energy spectrum analysis method is to calculate the energy ratio of the first frequency range and the second in the frequency domain atlas. The energy ratio of the frequency range, wherein the energy ratio of the first frequency range=the energy of the first frequency range/total energy*100%; the energy ratio of the second frequency range=the energy of the second frequency range/total energy*100%. 10. The power transformer on-load tap changer vibration signal monitoring system and method according to claim 8, characterized in that, the first frequency range is 0-10KHz, and the second frequency range is 10KHz-20KHz .